1. Field of the Invention
The present invention relates to the field of microwave heating. In particular, the present invention relates to a microwave heating device comprising a feeding structure enabling the device to operate in substance independently of the load to be heated.
2. Description of the Related Art
The art of microwave heating involves feeding of microwave energy into a cavity. When heating a load in the form of e.g. food by means of a microwave heating device, there are a number of aspects which have to be considered. Most of these aspects are well-known to those skilled in the art and include, for instance, the desire to obtain uniform heating of the food at the same time as a maximum amount of available microwave power is absorbed in the food to achieve a satisfactory degree of efficiency. In particular, the operation of the microwave heating device is preferably independent of, or at least very little sensitive to, the nature of the load to be heated.
In European patent EPO478053, a microwave heating device in the form of a microwave oven cavity being supplied with microwaves via an upper and a lower feed opening in a side wall of the oven cavity is disclosed. The supply is made via a resonant waveguide device having a Q-value which is higher than the Q-value/s of the loaded cavity. The waveguide is so dimensioned that a resonance condition is established in the waveguide device. The resonance condition gives a phase lock of the microwaves at the respective feed openings, where the phase lock preferably is in synchronism with the desired cavity mode/s.